In optics, an optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum. Common types of optical waveguides include optical fiber and rectangular waveguides. Optical waveguides can be employed as components in integrated optical circuits or as a transmission medium in local and long haul optical communication systems.
In electronic systems, a heat sink is a passive component that cools a device by dissipating heat into the surrounding air. Heat sinks can be employed to cool electronic components such as high-power semiconductor devices, and optoelectronic devices such as higher-power lasers and light emitting diodes (LEDs).
Flip chip, also known as controlled collapse chip connection or its acronym, C4, is a method for interconnecting semiconductor devices, such as IC chips, to external circuitry with solder bumps that have been deposited onto chip pads. The solder bumps can be deposited on the chip pads on a top side of a wafer during a final wafer processing step. In order to mount the IC chip to external circuitry (e.g., a circuit board), the IC chip is flipped over so that the IC chip's top side faces down, and aligned so that the IC chip's pads align with matching pads on the external circuit, and then the solder is flowed to complete the interconnect.